Create Captcha Code in HTML and Javascript

Hi friends, in this tutorial, you will learn how to create captcha code in HTML and Javascript. There are various ways to generate captchas such as Google ReCaptcha and other captchas etc.

Also read, Google Maps Add Marker Using Maps Javascript API and HTML

The logic of captcha code in HTML and Javascript

• First of all, we will call a function with the javascript onclick event handler to the input captcha field to generate the 4-digit random captcha code. The captcha code will load automatically when the page opens. Each time a captcha will be generated after clicking the refresh button.
• Now, we will use the javascript onsubmit event handler to the HTML form to validate the captcha. Suppose if a user hits the submit button without entering the captcha code then the function within the submit event handler will return false i.e. it prevents the HTML form to submit and an error message will be shown to the user.
• If you enter the wrong captcha then you will receive an error message otherwise you will receive a success alert for the correct captcha.

Also, you have to disable the copy text from the captcha field so that the captcha can not be copied. In order to do so, add the below lines of code inside the script tag.